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(*                       Readme file of                                    *)
(*            System Dynamics Simulation Modeling Tools                    *)	
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(*                       Tsae-Feng Yu                                      *)
(*                        Dec. 1 1994                                      *)
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1. Introduction

The software contains the simulation modeling tool that enables the user to
do simulation using system dynamics approach. Basically, the tool can be
viewed as three parts. The first part, system dynamics graph editor, is
a graphical user interface allowing the user to edit system dynamics grpahs.
Several editing icon buttons facilitate the grpah editing, including the
creation of level, rate, auxiliary, constant and source/sink nodes. In 
addition, the user is allowed to modify the graph by moving, deleting and
text-changing functions. Once a system dynamics graph is completed, the user
can save it into the file using the name that he/she prefers and load it back
later on. 

The second part is about the generation of differential equations for the
currently editing system dynamics graph. When a system dynamics graph is 
finished, a set of abstract equations representing the relationships 
between/among the nodes on the graph are generated by the software. The user 
needs to input the expressions to complete the equations before the simulation
execution. Once all equations are modified, the system directly goes to the 
third part, simulation execution.

The last part,simulation execution module, is based on the equations input by 
the user to generate a set of executable codes. To directly execute a 
pre-existing system dynamics model, the user can press the "simulation 
execution" icon.  The other way to enter the simulation execution window is 
after completing the input of differential equations. When the simulation 
execution window shows up, the user is still allowed to modify the equations 
and input some required initial values. Once the required data are completed, 
the user can start the execution by pressing "execution" button. After a short 
execution time, depending on the number of simulation iterations, the 
simulation result window is poped up and allow the user to make selections of 
displaying all individual results or a single graph containing all results on 
2D graphs.


2. How to start the system

	In the directory, type "sdsmt" to execute the tool. ("sdsmt" stands
for System Dynamics Simulation Modeling Tools.)

3. File descriptions of the tool

	The simulation tool is developed using Tk/Tcl scripting lagnauge.
Except the main program, "sdsmt", all executable programs are named with
the suffix,".tcl" and are listed in the following.

	display1.tcl    // show simulation result display selections
	draw.tcl        // draw node/link objects on canvas
	file.tcl        // load, save file procedures
	plot.tcl	// plot 2D graphs
	do.tcl          // activate each file function
	equ.tcl         // equation genration and execution
	help.tcl        // online help menu
	set.tcl 	// set mode changes

	The naming used for system dynamics graph, equation and initial value
files is based on the following regulations.

	.sdg		// system dynamics graph
	.sdg.equ	// a set of equations of a specific SD graph
	.sdg.init	// the initial values for execution purpose

	Required bitmap files and data are stored in subdirectories, "bitmap"
and "XBM".

4. Feedback

	Since the tool is developed as a one-semester project, some bugs or
errore may be inevitable.  The user is encouraged to provide feedback about 
the tool. Please send any comments or suggestions to yu@cis.ufl.edu. Your 
assistance will be appreciated.
